For $400 you can probably do pretty well though the old weight vs. stability issue will be a big factor. FWIW, carbon fiber is not the absolute answer. Yes, it is light, but have you noticed that the capacity ratings for most CF legs are less than for similar metal models from the same manufacturer?
I came in at about $300 for my setup. You can read the full story in the first several posts of the Tripod Reviews thread:
https://www.pentaxforums.com/forums/pentax-camera-field-accessories/45466-tripod-reviews.html
and the ball head review here:
https://www.pentaxforums.com/forums/pentax-camera-field-accessories/45654-bal...301-656-a.html
Here is a photo of the combo in action:
After two years, I am still very happy with my purchase and have found the legs and head quite adequate for most of my purposes. It has supported everything from my rangefinder 35mm film cameras to my 4x5 view camera with no issues related to stability. It is also relatively light and compact given its capacity. That being said, I found that for much of the shooting I do with lighter kit, it is overkill.
As a result, I recently bought a second set-up that only weighs about 2.5 pounds and is very adequate for my 35mm film cameras and can also be used for the K10D with lighter lenses (i.e. everything except the large zooms that I don't use and can't afford). The magical tripod is the Slik 330 DX with a Manfrotto 494 mini ball head substituting for the tilt/pan head that came with the legs. Total price including the B-M 494 was about $150. In my opinion, it is a killer combination for travel and hiking.
I will be posting a full review on this forum in a few weeks.
Steve